This invention generally relates to imaging technologies and, more particularly, to apparatus for imaging biological tissue samples such as a breast of a living human using techniques such as photoacoustic or thermoacoustic tomography.
A variety of different devices have been developed for imaging biological samples such as breast tissue. One example of such imaging technology is X-ray mammography. This technology has been used for some time to detect soft tissue anomalies that may indicate breast cancer. Early detection and treatment significantly improves prognoses. As a result of this technology, countless deaths due to breast cancer have been avoided.
One drawback of conventional mammography techniques is that the tissue must be relatively thin to obtain meaningful results, requiring tightly squeezing the breast between a pair of plates. A radiographic source is positioned on one side of the plates and a radiographic detector is positioned on the other side of the plates so an image radiographic image can be obtained. Squeezing the breast can be painful for the person being screened. As a result, some women do not receive mammography screening as frequently as recommended and other women avoid screenings all together. Thus, mammography is less successful than it might be if the procedure was less painful. In addition, mammography involves the use of ionizing radiation, which carries a risk of causing cancer. Accordingly, there is a need for a imaging technique that offers high resolution detection but avoids causing the patient pain.
Thermoacoustic tomography and photoacoustic tomography are techniques in which electromagnetic impulses are directed toward soft tissue to induce ultrasonic waves in the tissue. The ultrasonic waves are measured to determine dielectric and/or optical properties of the tissue. These properties are related to the physiological and pathological health of the tissue. Thermoacoustic tomography uses electromagnetic radiation in the radiofrequency and/or microwave bands, and photoacoustic tomography uses electromagnetic radiation in the visible light and/or near infrared light bands to induce the ultrasonic waves in the tissue. These non-invasive and non-ionizing imaging techniques have a potential to provide high imaging contrast and improved and more accurate cancer diagnoses.